Logging devices which measure formation dielectric constant are known, for example from U.S. Pat. No. 3,849,721 and U.S. Pat. No. 3,944,910. The logging device includes a transmitter and spaced receivers mounted in a pad that is urged against a bore hole wall. An electromagnetic (EM) microwave is transmitted into the formations, and the wave which has propagated through the formations is received at the receiving antennas. The phase shift and attenuation of this wave propagating in the formations is determined from the receivers output signals. The dielectric constant and the conductivity of the formations can then be obtained from the phase shift and attenuation measurements. Two transmitters are generally used in a bore hole compensated array to minimize the effect of bore hole rugosity, tool tilt, and dissimilarities in the transmitters, receivers, and their electronic circuits.
These types of probes had limited accuracy, which was improved by the architectural arrangement described in European Patent Publication No EP 1 693 685 published on 23 Aug. 2006. This arrangement proposed the use of a different spacing, frequency or wave polarization for performing EM measurements of the downhole formation.